[Keywords:] three-plate mold; automatic stripping; mold outside the distance type; fixed mold limit ejection shampoo bottle cap injection mold design Abstract: Take the common head of the sea silk shampoo cap as an example to further explain the mold design In philosophy, it is important to have bold, flexible and broad thinking skills.
1 Product Structure and Process Analysis (1) Product Name: Head & Shoulders shampoo bottle cap is shown in Figure 1 (figure omitted).
(2) Product material and appearance analysis.
Shampoo bottle caps are appearance products and have strict appearance requirements:
1 appearance gloss;
2 Material: PP+GF20% (light blue), shrinkage: 1.5%.
Polypropylene (PP) is a crystalline plastic with excellent fluidity and low hygroscopicity. Melt cracking may occur. The mold temperature should not be too high (80°C～90°C) and the cooling speed is fast. Therefore, the gating system and cooling system should be cooled slowly. Its molding shrinkage range, shrinkage, shrinkage, dents, deformation, directional, strong, injection molding should be strictly controlled temperature, low material temperature direction is obvious, especially at low temperature and high pressure, mold temperature is low The plastic parts below 50°C are not glossy, and they are prone to poor welding and flow marks. When the mold temperature is higher than 90°C, they are prone to warping and deformation. The thickness of the plastic parts is required to be uniform, and the notches and sharp corners should be avoided to prevent molding. Stress concentration. The mold should be designed with enough exhaust.
The wall thickness of polypropylene (PP) material should not be less than 0.85mm.
The product molding wall thickness is lower than 0.85mm, in order to increase product strength, it needs to be modified plus GF15%.
(3) analysis of product forming structure.
This product has a relatively thin wall thickness (0.80mm). It is prone to warping and deformation during molding. The fit between the small cover tip and the large cover tip should be tight and should not be loosened. The shape of the small cover should not be too thin or thick. Should have enough folding and easy to fold, the rubber-shaped shrapnel arc should not be too long, to ensure that the small cover buckle, the surface without arch, anastomosis exactly.
The internal structure of the product is difficult to form:
1 The overall position of the internal structure will determine the appearance of the cap and body after assembly with the bottle body;
2 The inner structure and the inner part of the bottle mouth are thinner, and the diameter and height should ensure that the assembly can reach into the bottle mouth after assembly and can swell the inner wall to play a sealing role so that the shampoo can not flow out from the inside of the bottle cap;
3 This shampoo bottle cap is a bulging (internal rib) lock on the outer rib of the bottle, shampoo bottle cap ribs should not be molded after the release;
4 The round wall where the inner rib of the bottle cap is located has a symmetrical opening. When the bottle cap is locked, the round wall elastically expands. The inner rib of the bottle cap is difficult to process on the mold core (the symmetry of the core cylindrical surface is convex From).
(4) Determine the mold structure.
1 In order to ensure the appearance of the product, the center of the top surface of the product (small cover surface) is used to enter the plastic - a three-plate die direct injection port;
2 When the bottle cap is formed, the small cap is opened. The small cap core must be installed on the A template. This must be removed from the fixed mold when the mold is opened, so as to ensure that the small cap is not damaged and the large cap is closed. Connection; mold must have a reliable fixed mold ejection structure - fixed mold ejection;
3 Taking into account the forming factor, 1 cavity and 4 cavity are used. The gate plate is required and the mold is divided. The gate of this mold is designed to fall off automatically. The mold needs to have a distance-fixing device on the parting surface of the gate plate. ;
4 Optimized design of ejector ejector system - Inclined-top principle (ie: core ejector ejection).
The shape of the shampoo bottle cap is roughly elliptical, the thickness of the molding wall is thin, and the bottle cap has internal ribs, and the force is relatively small. Forced demolding is required. Larger demoulding force is required. According to the inclined roof principle, the moving mold demoulding method is designed. As the core is inclined out, the top output force is relatively large and reliable, and the dynamic die ejector system has a simple structure.
2 mold structure and its working process (1) mold structure 1 according to the polypropylene (PP) cooling speed, the casting system and the cooling system should be slow heat characteristics, the mold mold part of the product molding is less, so the mold fixed part will No cooling system.
2 The hot runner will not be designed for this mold casting system because polypropylene (PP) is sensitive to temperature and the temperature should not be controlled.
3 Because polypropylene (PP) is more sensitive to temperature, the mold heater can not be too much (heating rod), need to be installed in the mold in order to better control the mold temperature, but not too close to the cavity.
(2) analysis of molded parts design.
1 cavity design.
The cavity is the main part of the outer surface of the molded product. The product has strict requirements on the outer surface of the molding, and takes into account the large production volume of the product. In order to improve the strength and stiffness of the mold, the cavity is easy to process and replace, etc., so the cavity uses the whole Insert type, material imported P20.
2 core design.
The core is the main part of the internal surface and structure of the molded product. There are many cores in the product, especially the fixed mold, which brings certain difficulties to the mold assembly precision. The core parts will be manufactured when the mold is repaired and the parts are replaced later. Accuracy makes it difficult.
The important part of the mold design: the use of dynamic model core slid out of the mold ejection.
3 fixed mold ejection design points.
There are two types of mold ejection: in-mold and out-mold:
a. Outer die ejector force is larger (usually pneumatic device, plastic die ejector ejector part is larger), and the pneumatic ejector speed is fast, the same speed with the mold open. (To be continued)
1 Product Structure and Process Analysis (1) Product Name: Head & Shoulders shampoo bottle cap is shown in Figure 1 (figure omitted).
(2) Product material and appearance analysis.
Shampoo bottle caps are appearance products and have strict appearance requirements:
1 appearance gloss;
2 Material: PP+GF20% (light blue), shrinkage: 1.5%.
Polypropylene (PP) is a crystalline plastic with excellent fluidity and low hygroscopicity. Melt cracking may occur. The mold temperature should not be too high (80°C～90°C) and the cooling speed is fast. Therefore, the gating system and cooling system should be cooled slowly. Its molding shrinkage range, shrinkage, shrinkage, dents, deformation, directional, strong, injection molding should be strictly controlled temperature, low material temperature direction is obvious, especially at low temperature and high pressure, mold temperature is low The plastic parts below 50°C are not glossy, and they are prone to poor welding and flow marks. When the mold temperature is higher than 90°C, they are prone to warping and deformation. The thickness of the plastic parts is required to be uniform, and the notches and sharp corners should be avoided to prevent molding. Stress concentration. The mold should be designed with enough exhaust.
The wall thickness of polypropylene (PP) material should not be less than 0.85mm.
The product molding wall thickness is lower than 0.85mm, in order to increase product strength, it needs to be modified plus GF15%.
(3) analysis of product forming structure.
This product has a relatively thin wall thickness (0.80mm). It is prone to warping and deformation during molding. The fit between the small cover tip and the large cover tip should be tight and should not be loosened. The shape of the small cover should not be too thin or thick. Should have enough folding and easy to fold, the rubber-shaped shrapnel arc should not be too long, to ensure that the small cover buckle, the surface without arch, anastomosis exactly.
The internal structure of the product is difficult to form:
1 The overall position of the internal structure will determine the appearance of the cap and body after assembly with the bottle body;
2 The inner structure and the inner part of the bottle mouth are thinner, and the diameter and height should ensure that the assembly can reach into the bottle mouth after assembly and can swell the inner wall to play a sealing role so that the shampoo can not flow out from the inside of the bottle cap;
3 This shampoo bottle cap is a bulging (internal rib) lock on the outer rib of the bottle, shampoo bottle cap ribs should not be molded after the release;
4 The round wall where the inner rib of the bottle cap is located has a symmetrical opening. When the bottle cap is locked, the round wall elastically expands. The inner rib of the bottle cap is difficult to process on the mold core (the symmetry of the core cylindrical surface is convex From).
(4) Determine the mold structure.
1 In order to ensure the appearance of the product, the center of the top surface of the product (small cover surface) is used to enter the plastic - a three-plate die direct injection port;
2 When the bottle cap is formed, the small cap is opened. The small cap core must be installed on the A template. This must be removed from the fixed mold when the mold is opened, so as to ensure that the small cap is not damaged and the large cap is closed. Connection; mold must have a reliable fixed mold ejection structure - fixed mold ejection;
3 Taking into account the forming factor, 1 cavity and 4 cavity are used. The gate plate is required and the mold is divided. The gate of this mold is designed to fall off automatically. The mold needs to have a distance-fixing device on the parting surface of the gate plate. ;
4 Optimized design of ejector ejector system - Inclined-top principle (ie: core ejector ejection).
The shape of the shampoo bottle cap is roughly elliptical, the thickness of the molding wall is thin, and the bottle cap has internal ribs, and the force is relatively small. Forced demolding is required. Larger demoulding force is required. According to the inclined roof principle, the moving mold demoulding method is designed. As the core is inclined out, the top output force is relatively large and reliable, and the dynamic die ejector system has a simple structure.
2 mold structure and its working process (1) mold structure 1 according to the polypropylene (PP) cooling speed, the casting system and the cooling system should be slow heat characteristics, the mold mold part of the product molding is less, so the mold fixed part will No cooling system.
2 The hot runner will not be designed for this mold casting system because polypropylene (PP) is sensitive to temperature and the temperature should not be controlled.
3 Because polypropylene (PP) is more sensitive to temperature, the mold heater can not be too much (heating rod), need to be installed in the mold in order to better control the mold temperature, but not too close to the cavity.
(2) analysis of molded parts design.
1 cavity design.
The cavity is the main part of the outer surface of the molded product. The product has strict requirements on the outer surface of the molding, and takes into account the large production volume of the product. In order to improve the strength and stiffness of the mold, the cavity is easy to process and replace, etc., so the cavity uses the whole Insert type, material imported P20.
2 core design.
The core is the main part of the internal surface and structure of the molded product. There are many cores in the product, especially the fixed mold, which brings certain difficulties to the mold assembly precision. The core parts will be manufactured when the mold is repaired and the parts are replaced later. Accuracy makes it difficult.
The important part of the mold design: the use of dynamic model core slid out of the mold ejection.
3 fixed mold ejection design points.
There are two types of mold ejection: in-mold and out-mold:
a. Outer die ejector force is larger (usually pneumatic device, plastic die ejector ejector part is larger), and the pneumatic ejector speed is fast, the same speed with the mold open. (To be continued)
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